The present invention relates to magnetoresistive memory technology, and more particularly to an analog to digital converter using a memory array of multi-state magnetoresistive memory elements in which a received analog signal is proportionally distributed among the memory elements to program the memory array.
Magnetoresistive memory technology is currently being developed for memory devices such as magnetoresistive random access memory (MRAM) devices and the like. Integration of MRAM technology into complimentary metal oxide semiconductor (CMOS) is also currently being developed. Various MRAM technologies, fabricating methods, and related capabilities are described in various issued patents, including U.S. Pat. No. 5,940,319 entitled xe2x80x9cMagnetic Random Access Memory and Fabricating Method Thereofxe2x80x9d, U.S. Pat. No. 5,732,016 entitled xe2x80x9cMemory Cell Structure in a Magnetic Random Access Memory and a Method For Fabricating Thereofxe2x80x9d, and U.S. Pat. No. 5,703,805 entitled xe2x80x9cMethod For Detecting Information Stored in a MRAM Cell Having Two Magnetic Layers in Different Thicknessesxe2x80x9d, which are hereby incorporated by reference in their entirety.
In general, a magnetic memory element has a structure which includes ferromagnetic layers separated by a non-magnetic layer. Information is stored as directions of magnetization vectors in magnetic layers. Magnetic vectors in one magnetic layer, for instance, are magnetically fixed or pinned, while the magnetization direction of the other magnetic layer is free to switch between the same and opposite directions as information which are called xe2x80x9cParallelxe2x80x9d and xe2x80x9cAntiparallelxe2x80x9d states, respectively. In response to Parallel and Antiparallel states, the magnetic memory element represents two different resistances. The resistance indicates minimum and maximum values when the magnetization vectors of two magnetic layers point in substantially the same and opposite directions, respectively. Accordingly, a detection of changes in resistance allows an MRAM device to provide information stored in the magnetic memory element.
MRAM technology is very versatile and cost effective and is intended to replace other memory types including FLASH-type memories, dynamic RAMS (DRAMs), static RAMs (SRAMs), etc. Memory devices are usually only part of an overall system which may further include processing devices, controllers, and various other analog functional modules and devices. The challenge is to incorporate MRAM technology in the most efficient and cost effective manner.